The present invention is directed generally to fiber optic switches and, in particular, to 1xc3x97N and dual 1xc3x972 switches with minimal optical losses that can accommodate a large number of possible switch connections, e.g., N may range from 2 to 100 or so, using reflection of the optical beam to achieve switching, especially having improved switching speed and repeatability.
Many types of fiber optics switches are in the market now. A number of patents are exemplary of the type of optical switches currently commercially available; see, e.g., U.S. Pat. No. 4,378,144, entitled xe2x80x9cOptical Switchxe2x80x9d and issued on Mar. 29, 1983, to G. S. Duck et al; U.S. Pat. No. 4,896,935, entitled xe2x80x9cFiber Optic Switchxe2x80x9d and issued on Jan. 30, 1990, to H. -S. Lee; U.S. Pat. No. 5,005,934, entitled xe2x80x9cFiber Optics Channel Selection Devicexe2x80x9d and issued on Apr. 9, 1991, to L. E. Curtiss; and U.S. Pat. No. 5,420,946, entitled xe2x80x9cMultiple Channel Optical Coupling Switchxe2x80x9d and issued on May 30, 1995, to J. -H. Tsai. To make a compact design, the fibers may be arranged differently, see, e.g., U.S. Pat. No. 5,629,993, entitled xe2x80x9cCompact Optical Switchxe2x80x9d and issued on May 13, 1997, to J. O. Smiley.
All of the foregoing designs depend on difficult-to-attain precise mechanical alignment. For example, in U.S. Pat. Nos. 4,378,144, 4,896,935, 5,420,953, and 5,629,993, the alignment is between moving and stationary parts, while in U.S. Pat. No. 5,005,934, the alignment is between stationary parts which are far away from each other.
U.S. Pat. No. 5,173,958, entitled xe2x80x9cBeam Distributor for Laser-to-Optical Fiber Applicationxe2x80x9d and issued on Dec. 22, 1992, to M. F. Folsom et al, discloses an eccentrically mounted retroreflector prism in a cylindrical housing having a plurality of lenses and associated optical fibers distributed about the central axis of the housing. The prism is driven to revolve about the central axis and, as it does so, to sequentially direct a beam which is incident along the central axis to respective lenses and optical fibers in turn, by retroreflection. A drawback with this arrangement is the use of a prism retroreflector comprising a bulk prism. Such a bulk prism adds weight to the system and its front face introduces unwanted light reflection.
U.S. Pat. No. 5,481,631, entitled xe2x80x9cOptical Switching Apparatus with Retroreflectorxe2x80x9d and issued on Jan. 2, 1996, to J. E. Cahill et al, discloses use of a retroreflector, or corner cube reflector, mounted on a stepper motor to be selectively positioned so as to direct light from one optical fiber to another. However, the reference does not describe how the retroreflector is constructed.
Thus, what is needed is a fiber optics switch where all alignments are between parts that are in relatively close proximity to each other and do not have relative motion. Ideally, a compact design is desired, to reduce space requirements. Also ideally, the optical fibers should be stationary. Finally, the retroreflector must be reconfigured to reduce weight and increase switching speed.
In accordance with the present invention a 1xc3x97N reflector switch for switching an optical signal from one optical fiber to any of N optical fibers is provided. The 1xc3x97N reflector switch comprises:
(a) an input beam-forming unit, situated along an axis and comprising the optical fiber and a lens secured thereto, the input beam-forming unit emitting an optical input signal;
(b) N output beam-forming units disposed around the axis and parallel to the input beam-forming unit, the output beam-forming units each comprising an optical fiber and a lens secured thereto, each output beam-forming unit accepting an optical output signal;
(c) a truncated, hollow reflector assembly for reflecting the input optical signal from the input beam-forming unit to any of the N output beam-forming units; and
(d) a mechanism for rotating the reflector assembly to align the input optical signal from the input beam-forming unit with any of the output beam-forming units.
Also in accordance with the present invention, a 1xc3x972 reflector switch for switching optical signals from a first set of two optical fibers to a second set of optical fibers is provided The 1xc3x972 reflector switch comprises:
(a) three beam-forming units, each comprising an optical fiber and a lens secured thereto, beam-forming units disposed on three corners of a square symmetrically disposed about an axis, with one beam-forming unit thereby having two adjacent neighboring beam-forming units;
(b) two rotatable reflector assemblies, in parallel, disposed symmetrically about the axis, arranged such that an optical signal from the one beam-forming unit is reflected into one of the adjacent beam-forming units, and, upon 90xc2x0 rotation of the two rotatable reflector assemblies, the optical signal is reflected into the other of the adjacent beam-forming units; and
(c) a mechanism for rotating the two rotatable reflector assembly to alternately align the optical signal between the two adjacent beam-forming units.
Further in accordance with the present invention, a dual 1xc3x972 reflector switch, or 2xc3x972 reflector switch, for switching optical signals from a first set of two optical fibers to a second set of optical fibers is provided. The dual 1xc3x972 reflector switch comprises:
(a) two first beam-forming units and two second beam-forming units symmetrically disposed in a square about an axis, each beam-forming unit comprising an optical fiber and a lens secured thereto, with the two first beam-forming units diagonally disposed about the axis;
(b) two rotatable reflector assemblies, in parallel, disposed symmetrically about the axis, arranged such that the optical signal from each first beam-forming unit is reflected into each one of the second beam-forming units, respectively, and, upon 90xc2x0 rotation of the two rotatable reflector assemblies, the optical signals are each reflected into each other of the second beam-forming units, respectively; and
(c) a mechanism for rotating the two rotatable reflector assembly to alternately align the optical signal between the first set of second beam-forming units and the second set of beam-forming units.
The present invention is directed to a fiber optics switch design in which all alignments are between parts that are in close proximity to each other and do not have relative motion. As a side benefit, very compact design is achieved, for example, on the order of about 25 mm diameter for a completed switch. Also, the fibers are stationary, which improves their life.
Other objects, features, and advantages of the present invention will become apparent upon consideration of the following detailed description and accompanying drawings, in which like reference designations represent like features throughout the FIGURES.